Removable Protective Lip on a Wiping Element

ABSTRACT

The invention relates to a wiping element ( 1 ) made of a rubber-elastic or ductile-elastic material for the protection of components mobile against one another, wherein at least one wiping lip ( 2 ) is provided on the wiping element ( 1 ). The wiping element ( 1 ) has a protective lip ( 4 ), which is or can be fixed in a detachable fashion to the wiping element ( 1 ). In a wiper arrangement ( 10 ), the wiping element ( 1 ) is arranged position-stable on a first component and lies with the wiping lip ( 2 ) and the protective lip ( 4 ) adjacent to a second component. With the use of such a wiper arrangement ( 10 ) for the painting of components mobile against one another, at least one component is painted in the fixed state of the protective lip ( 4 ) and the protective lip ( 4 ) is then detached from the wiping element ( 1 ).

The invention relates to a wiping element made from a rubber-elastic orductile-elastic material for the protection of components mobile againstone another, at least one wiping lip being provided on the wipingelement.

Such wiping elements are described for example in the textbook “HeinzKonrad Müller, Abdichtung bewegter Maschinenteile, Medienverlag, 1990”(page 192) and are known as part of a wiper arrangement from DE 196 39798.

Wiping elements are used in systems of components mobile against oneanother in order to protect the latter against the entry of foreignsubstances. The wiping element is as a rule arranged upstream of afurther seal. The wiping lip provided on the wiping element liesadjacent to the component which is exposed to the ambient conditions inthe extended state and wipes off particles of dirt, ice, water and otherforeign substances adhering to the component, before the component isretracted into the system again. In a cylinder-piston unit, the pistonrod to be retracted is kept free from foreign substances by a wipingelement.

The systems protected by wiping elements are often hydraulic. Foreignparticles that have entered into a hydraulic system can lead to damageto seals, guides, valves and pumps. The components mobile against oneanother may also be damaged. The foreign particles can for example getunder a downstream seal lying adjacent to a component under highpressure and, during the counter-movement of the components, damage atleast one of the components. Furrows thus arise on the piston rod in acylinder-piston unit during the retraction and extension of the pistonrod.

The furrows on the piston rod can in turn damage the wiping lip of awiping element arranged upstream and thus impair the wiping element inits function.

The penetration of foreign substances is largely prevented by suitablewiping elements in the running operation of a hydraulic system. Damageand contamination on external areas of retracted components can howeveralso occur before commissioning, in particular during transport andduring assembly.

Systems of components mobile against one another such as acylinder-piston unit are transported as a rule with a wiping elementalready assembled. For the purpose of protection against corrosion, theexternal area of a retracted component, for example the external pieceof a piston rod, is wetted with wax or grease. This kind of preservationhas proved to be inadequate, especially in the case of transport byship. The components may be damaged even before commissioning, as aresult of which the hydraulic system as a whole may be impaired.

The components of a hydraulic system are as a rule painted afterassembly. In the painting process, paint particles can get into theregion of components whose surfaces are to be sealed against one anotherunder high pressure. Due to temperature differences occurring in thecourse of the painting process, a component may be traversed to adiffering extent against an adjacent component, as a result of which adrift area adjacent to the wiping element arises. The drift area of thecomponent and the paint particles adhering to it are introduced into thehydraulic system following the painting process due to a cooling-relatedretraction of the component. The paint particles, like other foreignsubstances, have the initially described harmful effects on a hydraulicsystem. A hydraulic system can thus already be contaminated with foreignparticles before commissioning, as a result of which the functionalityof the wiping and sealing elements and the overall system may beimpaired.

External areas of retracted components adjacent to the wiping element,in particular the drift area, are protected during painting with the aidof an upstream element, for example, an adhesive tape, a molded part oran O-ring. After the painting process, the protective devices areremoved. The devices known from the prior art for the protection of thedrift area require additional work for their fitting. In particular, thefitting of a well functioning protective device, a suitable adhesivetape for example, requires great care and a great deal of work.

The problem underlying the invention is to protect in a straightforwardmanner external areas of a traversable component adjacent to a wipingelement in a system of components mobile against one another.

According to the invention, the problem is solved by the fact that thewiping element has a protective lip, which is provided in a detachablefashion on the wiping element.

The protective lip provided on the wiping element according to theinvention is arranged upstream of a wiping lip and like the wiping lipalso lies adjacent to the component to be protected, so that theprotective lip covers the area of the component lying between thecontact line of the protective lip and the contact line of the wipinglip and said area is protected against influences from the environmentsuch as corrosive or paint particles.

The protective lip according to the invention simplifies transport,assembly and commissioning of a system of components mobile against oneanother. The protective lip can already be fixed to the wiping elementduring transport, as a result of which the use of additionalpreservation agents is not necessary. The wiping element is fittedtogether with the protective lip on a component before painting. As aresult of the incorporation of a suitable protective device on thewiping element, there is no need for the time- and cost-intensivefitting of an additional protective device, such as for example anadhesive tape.

The protective lip is provided on the wiping element in a detachablefashion, as a result of which the advantage arises that the protectivelip can be detached and removed from the wiping element after use, i.e.after transport or after painting of the components mobile against oneanother. Removal of the protective lip requires a small amount of workcompared with conventional protective devices.

In a preferred embodiment of the wiping element according to theinvention, the protective lip is produced from a rubber-elastic orductile-elastic material, preferably the same material as the wipingelement, softer or harder than the material of the wiping element.

Rubber-elastic and ductile-elastic materials and composites of bothtypes of material are suitable for the production of wiping elements andfor making reliable wiping lips available. A protective lip producedfrom such a material exhibits the same properties as a correspondinglyproduced wiping lip, in particular it sits close to a component. Awiping element, whose protective lip and wiping lip are produced fromthe same material, is easy to handle on account of uniform elasticityand flexibility and lies with both lips adjacent to a component in thesame way. A protective lip that is produced from a softer material thanthe material of the wiping element has an advantageous sealing behaviorin respect of low-viscous liquids and in respect of very smallparticles. The production of the protective lip from a material which isharder than the material of the wiping element offers the advantage thatsuch a protective lip, as a more solid composite piece, can easily bedetached from the wiping element.

In a preferred development of the wiping element according to theinvention, the protective lip is fixed by a firm bond to the wipingelement, the firm bond being embodied uninterrupted or in segments,preferably as a perforation.

The advantage of this development lies in the fact that, as a result ofthe firm bond between them, the protective lip and the wiping elementform a unit which can be manufactured in the same production processand, in addition, assembled in a single step. The penetration of paintparticles or other foreign substances at the fixing edge between theprotective lip and the wiping element is eliminated with anuninterrupted firm bond, as a result of which the protective lipperforms its function in an ideal manner. On the other hand, asegment-like attachment of the protective lip is advantageous for thedetachment of the protective lip from the wiping element. A perforationunifies the advantages of the two forms of embodiment, since a firm bondembodied as a perforation at comparatively small sub-zones is permeableto particles and, due to a connection of the protective lip and wipingelement being present only in sections, guarantees easy detachment ofthe two shaped parts.

In a further development of the wiping element according to theinvention, means for the attachment of the protective lip are providedon the wiping element and/or on the protective lip, the attachment ofthe protective lip taking place by means of positive locking.

With this embodiment, the wiping element and the protective lip arepresent as separately produced shaped parts. The attachment of theprotective lip to the wiping element takes place by means of positivelocking of suitable means, which are provided on the wiping element, theprotective lip or on both shaped parts. The positive locking arisingthrough the joining of suitable attachment means prevents, in a similarfashion to a firm bond, the penetration of particles through the joiningseam. A protective lip attached by positive locking can easily bedetached from the wiping element. The attachment means are as a rule notdamaged by joining and by a subsequent detachment. Resulting from thisis the advantage that the protective lip can be replaced when required,for example in the case of a protective lip severely contaminated ordamaged during transport, which is to be used further for protectionduring the painting process. Furthermore, a protective lip to beattached and removed in a positive locking manner can be usedrepeatedly.

Furthermore, the protective lip preferably comprises one or moreprojections and the sealing element comprises recesses corresponding tothe shape of the projections.

The attachment of the protective lip takes place in this embodiment byclipping into or onto one another or latching projections and recessesformed on the wiping element and/or the protective lip. In order toachieve a firm attachment of the protective lip, the recesses are formedfor example in such a way that they are each engaged from behind by acorresponding projection and thus each form a dovetail joint. Azipper-like joining seam between the protective lip and the wipingelement is formed in an arrangement of the projections and the recessesat regular intervals along the edge of the wiping element and,respectively, along the protective lip.

In a further preferred development of the wiping element according tothe invention, at least one grip or strap is provided on the protectivelip.

A grip or a strap provided on the protective lip makes for easierhandling during detachment of the protective lip from the wipingelement. Such a detachment aid can be gripped and pulled away in thedetachment procedure and thus facilitates removal of the protective lip.A detachment aid is especially suitable for breaking through a firm bondor a perforation at one point and then detaching the complete attachmentof the protective lip by pulling on the detachment aid.

In a preferred development of the wiping element according to theinvention, the protective lip in the fixed state overlaps the wipingelement at least partially.

The partial areas of the wiping element overlapped by the protective lipare protected, as is the protected area of the piston rod, againstcorrosive particles during transport and paint particles during apainting process. The attachment of an overlapping protective lippreferably takes place at an inner line of the protective lip.

The invention further comprises a wiper arrangement with a wipingelement according to the invention and at least two components mobileagainst one another, wherein the wiping element is arrangedposition-stable on a first component and lies adjacent to a secondcomponent.

In the wiper arrangement according to the invention, the wiping elementis arranged along the sealing gap formed by two components mobileagainst one another. The components can be parts of a machine or a gearunit. The wiping element is held on the first component, for example ina groove. The wiping lip and the protective lip lie adjacent to thesecond component, so that the area of the second component lying betweenthe contact lines of the two lips is covered by the protective lip andlargely protected against ambient influences. A wiping element with anoverlapping protective lip is advantageous for such a wiper arrangement,since an overlapping protective lip can lie adjacent to both componentsand can thus cover the whole sealing gap.

The wiping element lies in an annular fashion on the second component ina preferred embodiment of the wiper arrangement according to theinvention.

The wiping element used in this wiper arrangement is closed in anannular fashion and represents a so-called wiping ring, which engagesaround the second component and lies adjacent to its wholecircumference. Emerging from this is the advantage that the protectivelip is also closed to form a ring and protects an annular area of thesecond component.

Furthermore, the first component is preferably a housing and the secondcomponent a piston rod of a piston guided in the housing.

The piston rod of a piston guided in the housing is exposed to ambientconditions during retraction and extension. In order to prevent theentry of foreign substances into the interior of the housing, a wipingelement is arranged on the housing in such a way that the wiping lip isadjacent to the piston rod. The wiping element is inserted for exampleinto the annular groove of a cylinder. The protective lip protects theexternal area of the retracted piston rod lying adjacent to the wipingelement both during transport and during the painting process.

In a further embodiment, the piston rod exhibits, viewed incross-section, a polygonal shape, in particular a round or oval shape.

The wiping element as a rule lies adjacent to the whole circumference ofthe piston rod. Teeth or wedges at the external face of the piston rodcan determine the polygonal shape of the cross-section of a piston rod.The wiping element and, as a result, also the protective lip follow thecontour of the polygonal shape. In this way, the protective lip and thewiping lip perform their function to the full extent. A round or ovalcross-section of the piston rod is advantageous with regard to thearrangement of the wiping element and the fitting and removal of theprotective lip.

The wiping element is a single or double wiper in a preferred embodimentof the wiper arrangement according to the invention.

Wiping elements are used for cleaning the piston rod to be retracted inhousing-piston units, which often represent a hydraulic system. Singlewipers have a wiping lip, which is arranged directed towards the housingexterior. The protective lip is arranged upstream of the wiping lip.Wiping elements can have a further wiping lip, which prevents the exitof oil out of the hydraulic system. So-called double wipers perform adouble sealing function, seal off hydraulic fluid towards the interiorand keep out foreign substances from the exterior. The protective lip isfitted in front of the outer wiping lip in the case of double wipers.

In a further preferred development of the wiper arrangement according tothe invention, the protective lip in the fixed state lies fluid-tightagainst the piston rod and/or the housing.

A fluid-tight fit of the sealing lip ensures that no fluids, such as forexample rain during transport or paint during the painting process,penetrate through the protective lip into the area to be protected. Anoverlapping protective lip lies adjacent both to the housing and to thepiston rod, so that the sealing gap lying around the piston rod iscompletely overlapped by the protective lip and both an area of thepiston rod lying beneath the protective lip and the wiping elementarranged in the sealing gap are protected in an ideal manner.

The invention further comprises the use of the wiper arrangementaccording to the invention for the painting of components mobile againstone another. In a first step, the wiping element is arranged and, asnecessary, the protective lip is fixed to the wiping element, in asecond step at least one of the two components mobile against oneanother is painted, and in a third step the protective lip is detachedfrom the wiping element after the painting process.

With the use of a wiper arrangement according to invention, theprotective lip fixed to the arranged wiping element protects the area ofthe component covered by it against contamination with paint particlesduring the painting process. It goes without saying that, as a rule, acomponent other than that against which the protective lip lies adjacentis painted. After the painting, the protective lip is detached andremoved. By using a wiper arrangement according to the invention forpainting, a system of components mobile against one another can becommissioned without preliminary damage caused by the painting process,in particular without contamination.

Further advantages of the invention emerge from the description and thefigures of the drawing. The wiping element according to the inventionand the wiper arrangement according to the invention are represented inthe examples of embodiment in FIGS. 1 to 5. The embodiments shown in thefigures are shown very much in schematic form and are not to beunderstood as being to scale. The individual reference numbers are usedto designate identical features in the different embodiments.

In the figures:

FIGS. 1 to 4 show a cross-section of an exemplary wiping element; and

FIG. 5 shows a section through an exemplary arrangement of a wipingelement in a housing-piston unit.

FIG. 1 shows a section crosswise through a wiping element 1 according tothe invention. Wiping element 1 is designed as a double wiper andcomprises at the lower side a wiping lip 2 and a further wiping lip 3. Aprotective lip 4 is fitted at an end face above wiping lip 2. Protectivelip 4 extends lengthwise downwards up to a contact face not shown in thefigure, to which wiping lip 2 and further wiping lip 3 also lieadjacent. The region of the contact area lying between the contact pointof protective lip 4 and that of wiping lip 2 is covered by protectivelip 4 and protected against ambient influences, such as corrosiveparticles. Protective lip 4 and wiping element 1 are produced from thesame ductile-elastic material. Protective lip 4 is fixed in a firmlybonded manner to wiping element 1. A perforation 5 is provided at thejoining point between protective lip 4 and wiping element 1, and thisenables a simplified detachment of protective lip 4 from wiping element1.

FIG. 2 represents a further inventive wiping element 1 with a wiping lip2 and a further wiping lip 3. A protective lip 4 is attached at thebase-shaped end edge above wiping lip 2. Protective lip 4 is fixed towiping element 1 by means of a narrow linear firm bond, provided withreference number 6 in cross-section. Protective lip 4 is attached at aninner line, so that protective lip 4 extends not only downwards up tothe contact face, but also upwards, and overlaps wiping element 1 at thefront side in a strip-like fashion. By means of this overlapping, notonly the area of the contact face and wiping lip 2 covered by protectivelip 4, but also the upper part of wiping element 1 are covered and atleast partially protected against influences from the surroundings, suchas for example paint particles. Protective lip 4 is made from arubber-elastic material, which is softer than the material of wipingelement 1. As a result, protective lip 4 exhibits a good sealingbehavior with respect to light-viscous fluids and very small particles.

FIG. 3 shows how protective lip 4 is fixed to wiping element 1 bypositive locking. Protective lip 4 and wiping element 1 are separatesections, which form a unit in the fixed state of protective lip 4represented here. A recess is provided in the end face above wiping lip2. Protective lip 4 has a projection 7 corresponding to the shape of therecess, said projection engaging behind the recess in such a way that adovetail joint arises. Protective lip 4 is produced from a composite ofrubber-elastic and ductile-elastic materials, which is harder than thematerial of protective lip 4. As a result, protective lip 4 represents aharder shaped piece, which can be detached from wiping element 1 withoutdamaging the wiping element 1. The described recesses can also beconfigured cylindrical so as to receive pins or bolts. Moreover,recesses on the protective lip and projections on the wiping element areconceivable.

FIG. 4 shows a wiping element 1 made of a rubber-elastic materialdesigned as a double wiper. Analogous to the representations alreadydescribed, a protective lip 4 is provided on an end face, saidprotective lip being fixed via a web 8 to wiping element 1. Web 8connects said end face to the centerline of protective lip 4. Protectivelip 4 lies at one end adjacent to an imaginary contact face and at theother end adjacent to the upper edge of the end face of wiping element1. Provided at the outward-facing side of protective lip 4 is ablock-shaped grip 9, with the aid of which protective lip 4 can bedetached from wiping element 1 by tearing off web 8. By means of suchwebs, protective lip 4 as a whole is attached, for example only insegments, to wiping element 1.

FIG. 5 represents a schematic section through a wiper arrangement 10according to the invention. In housing 11, a wiping element 1 isinserted in an annular groove und lies in an a annular fashion adjacentto piston rod 12 in the sealing gap between housing 11 and a piston rod12 of a piston guided in housing 11. Wiping element 1 has a singlewiping lip 2 as a single wiper. A protective lip 4 made of the samematerial as wiping element 1 is fixed to wiping element 1 at the endface above wiping lip 2, the attachment taking place by means of aperforation 5 similar to wiping element 1 represented in FIG. 1.Provided at the perforation edge is a strap 13, with the aid of whichthe perforation can be broken through in order to detach protective lip4. Wiping element 1 lies with protective lip 4 and wiping lip 2 adjacentto piston rod 12, so that the area between the two contact points iscovered by protective lip 4. The overlapping serves for the preservationof said area during transport of wiper arrangement 10 as well as forprotection during painting of housing 11. As a result of a fluid-tightfit of protective lip 4 on piston rod 12, no corrosive or paintparticles penetrate to the area to be protected. The area of piston rod12 lying adjacent to wiping lip 2 at the exterior can be run beneathwiping lip 2 due to paint-related temperature differences, as result ofwhich wiping element 1 and downstream seals become contaminated by dirtand paint particles adhering to piston rod 12 in this area. As a resultof this contamination, wiping element 1 and other seals and componentsof the housing-piston unit may be damaged and restricted in theirfunction. After painting of housing 11, protective lip 4 is detachedfrom wiping element 1 by pulling on strap 13 in the direction of arrow14 and removed from piston rod 12.

The invention relates to a wiping element 1 made from a rubber-elasticor ductile-elastic material for the protection of components mobileagainst one another, wherein at least one wiping lip 2 is provided onwiping element 1. Wiping element 1 has a protective lip 4, which is orcan be fixed in a detachable fashion to wiping element 1. In a wiperarrangement 10, wiping element 1 is arranged position-stable on a firstcomponent and lies with wiping lip 2 and protective lip 4 adjacent to asecond component. When such a wiper arrangement 10 is used for thepainting of components mobile against one another, at least onecomponent is painted in the fixed state of protective lip 4 andprotective lip 4 is then detached from wiping element 1.

1-14. (canceled)
 15. A wiping element made of a rubber-elastic orductile-elastic material for the protection of components mobile withrespect to one another, the wiping element comprising: at least onewiping lip formed on the wiping element; a protective lip disposed onthe wiping element in a detachable fashion; and at least one removal aiddisposed between said protective lip and the wiping element for removingsaid protective lip from the wiping element.
 16. The wiping element ofclaim 15, wherein said at least one removal aid is a grip or a strap.17. The wiping element of claim 15, wherein said protective lip isproduced from a rubber-elastic or ductile-elastic material.
 18. Thewiping element of claim 15, wherein said protective lip is made from asame material, a softer material, or a harder material than a materialof the wiping element.
 19. The wiping element of claim 15, wherein saidprotective lip is fixed by means of a firm bond to the wiping element,said firm bond being uninterrupted, in segments, or a perforation. 20.The wiping element of claim 15, wherein said removal means means areprovided on the wiping element and/or on said protective lip, attachmentof said protective lip taking place by means of positive locking. 21.The wiping element of claim 20, wherein said protective lip has one ormore projections and the wiping element has recesses corresponding to ashape of said projections.
 22. The wiping element of claim 15, whereinsaid protective lip, in a fixed state thereof, at least partiallyoverlaps the wiping element.
 23. A wiper arrangement comprising thewiping element of claim 15 and with at least two components mobile withrespect to one another, wherein the wiping element is arrangedposition-stable on a first component and seats on a second component.24. The wiper arrangement of claim 23, wherein the wiping element seatson the second component in an annular fashion.
 25. The wiper arrangementof claim 23, wherein the first component is a housing and the secondcomponent is a piston rod of a piston guided in the housing.
 26. Thewiper arrangement of claim 25, wherein the piston rod, viewed incross-section, has a polygonal, round or oval shape.
 27. The wiperarrangement of claim 26, wherein the wiping element is a single wiper ora double wiper.
 28. The wiper arrangement of claim 25, wherein saidprotective lip, in a fixed state thereof, lies fluid-tight against thepiston rod and/or the housing.
 29. A method for painting componentswhich move with respect to each other using a wiper arrangementincluding a wiper element made from rubber-elastic or a ductile-elasticmaterial, wherein at least one wiping lip is disposed on the wiperelement, the wiper element having a protective lip which is disposed onthe wiper element in a detachable fashion and with at least two machinecomponents which move relative to each other, the wiper element beingdisposed in stable position on a first machine component to seat on asecond machine component, the method comprising the steps of: a)disposing the wiping element with fixed protective lip on at least oneof the first and the second machine component; b) painting at least oneof the first and the second machine components; and c) detaching theprotective lip from the wiping element following step b).